Sutureless implantable device and method for treatment of glaucoma

ABSTRACT

Sutureless, implantable fluid shunting devices and associated methods for controlling the pressure of fluids within anatomical spaces or cavities of the body. The device generally comprises a tube having a diffusion barrier (e.g., diffusion chamber) formed on a proximal end thereof. Fluid which flows through the tube will collect within the diffusion chamber and will diffuse outwardly therethrough. However, the presence of the diffusion chamber will prevent microbes, cells or other matter from interfering with or backflowing through the tube. Additionally, the tube may be provided with a pressure-openable aperture through which fluid from the tube may flow into the diffusion chamber. Such pressure-openable aperture will remain closed, until the pressure of fluid within the tube exceeds a predetermined maximum pressure PMAX. In this manner, the pressure-openable aperture will limit the amount of fluid drained from the anatomical space or cavity of the body, thereby avoiding hypotony within such anatomical space or cavity. The diffusion barrier of the device is preferably configured to fit between, and to be engaged by, adjacent recti muscles of the eye. Such engagement of the diffusion barrier with the adjacent recti muscles serves to prevent unwanted migration or post-implantation movement of the device, without the need for suturing of the device to the tissue of the eye.

RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/738,332 filed Oct. 25, 1996 now U.S. Pat. No. 6,007,510entitled "Implantable Devices and Methods for Controlling the Flow ofFluids Within the Body."

FIELD OF THE INVENTION

The present invention relates generally to medical apparatus andmethods, and more particularly to a device which is implantable in amammalian body to control the pressure of fluid within a body cavity byshunting such fluid to another site within the body, when the fluidpressure within the body cavity reaches a pre-determined level.

BACKGROUND OF THE INVENTION

A number of diseases and disorders in humans and other mammals arecharacterized by the build-up of excessive fluid pressure within one ormore body cavities. In many instances, implantable devices or surgicalprocedures may be used to shunt excessive fluid from the body cavitywherein the excessive pressure build up is present, to one or more othersites within the body, as a means of receiving the undesirable pressurebuildup, and thereby deterring the development of undesirable sequelaewhich may result from such pressure build-up.

i. Glaucoma

Glaucoma is a disease of the eye which is characterized by highintraocular pressure, and is among the leading causes of blindness inthe world. In general, glaucoma results from a defect in the functionaldrainage system, whereby naturally occurring endogenous fluid (e.g.,aqueous humor) is drained from the interior of the eye. The result ofthis decreased functional drainage of the eye is three-fold: a)increased intraocular pressure, b) degeneration of the optic nerve andsupporting tissue at the optic nerve head (disk), and c) progressiveloss of the visual field.

Individual cases of glaucoma are generally classified, on the basis ofetiology, into two categories. These two major are "closed angleglaucoma" and "open angle glaucoma".

In closed angle glaucoma (syn. "angle-closure glaucoma", "narrow-angleglaucoma", "pupillary block glaucoma") excessive fluid accumulateswithin the anterior chamber of the eye due to the gradual closure of ananterior angle formed by the junction of the iris and the inner surfaceof the trabecular mesh work through which the aqueous humor is normallyreabsorbed. Closure of this anatomical angle prevents normal drainage ofaqueous humor from the anterior chamber of the eye.

In open angle glaucoma (syn. "chronic simple glaucoma" "simpleglaucoma", "wide-angle glaucoma") the angle of the anterior chamberremains normal, but the drainage of aqueous humor from the anteriorchamber is impeded or blocked by other means, such as edema or swellingof the trabecular spaces, abnormal pigment dispersion, ornon-perforating injury to the eye resulting in vascular congestion.

Various pharmacologic modes of treatment have been used to lessen theintraocular fluid pressure in glaucoma patients. Drugs which have beenadministered to treat glaucoma have included parasympathomimetic agentsof the choline ester type (e.g., bethanechol, carbachol andmethacholine), carbonic anhydrase inhibitors (e.g., acetazolamide),anticholinesterase agents (e.g., physostigmine, pilocarpine, demecarium,echothiophate and isoflurophate), sympathomimetic agents (e.g,epinephrine, phenylephrine) and β-adrenergic blocking agents (e.g.,tymolol). However, these various drug therapies for glaucoma aresometimes associated with significant untoward effects, includingheadache, blurred vision, allergic reactions, retinal detachment,phacodinesis, histological changes within the eye and potentialinteractions with other drugs.

As an alternative to pharmacologic modes of therapy, at least someglaucoma patients may be treated surgically by creating surgicalopenings into the anterior chamber of the eye, to facilitate drainage ofexcess aqueous humor from the anterior chamber. Many of these surgicaltechniques involve the formation of an opening or hole into the anteriorchamber, under the conjunctiva and/or scleral flap such that fluid willbe drained by filtration from the anterior chamber of the eye, into thetissues located within the lateral wall of the eye. The major problemsassociated with these surgical filtration procedures stem from the sizeof the opening or hole made into the anterior chamber. These problemsinclude hypotony, synechiae, inflammation, cataract, cornealdecompensation (edema), vitritis, choroidal separation (detachment),macular edema, and infections which may cause endophthalmitis. Moreover,such glaucoma filtration surgery is often unsuccessful due to theformation of dense fibrovascular connective tissue (e.g., scar tissue)around the surgical opening formed into the anterior chamber. Suchproliferation of connective tissue tends to close off thesurgically-formed opening into the anterior chamber, thereby deterringor preventing the desired filtration of aqueous humor into thesubconjunctival space.

In view of post-surgical complications associated with the developmentof fibrovascular connective tissue (e.g., scar tissue) around thesurgical site, a number of implantable drainage devices have been usedto ensure that the desired filtration and outflow of aqueous humorthrough the surgically-formed opening will continue, despite theformations of, scar tissue during the post operative period. Examples ofimplantable shunts or other implantable apparatus which have previouslybeen implanted into the eye for drainage of aqueous humor from theanterior chamber of the eye include those described in U.S. Pat. Nos.4,750,901 (Molteno), 5,041,081 (Odrich), 5,476,445 (Baerveldt),4,886,488 (White), 5,454,796 (Krupin), 5,397,300 (Baerveldt), 5,372,577(Ungerleider), 5,338,291 (Speckman, et al.), 5,300,020 (L'Esperance),5,178,604 (Baerveldt, et al.), 5,171,213 (Price), 5,092,837 (Klein etal.), 4,968,296 (Klein et al.), 4,946,436 (Smith), 4,936,825(Ungerleider), 4,886,488 (White), 4,806,382 (Burns et al.), 4,554,918(White), 4,521,210 (Wong), 4,428,746 (Mendez), 4,184,491 (McGannon),4,157,718 (Baehr), 4,030,480 (Meyer), 5,433,701 (Rubinstein), 5,346,464(Camras), 5,073,163 (Lippman), 4,604,087 (Joseph), 5,180,362 (Worst),5,520,631 (Li et al.).

The major disadvantage associated with the use of implantable shunts fortreatment of glaucoma is that, in the immediate post operative period,the shunt may facilitate excessive fluid drainage which results inhypotony within the anterior chamber, flattening of the anterior chamberand potential choroidal detachment and/or phthisis bulbi. Such excessivepost-operative fluid outflow may also result in expansion of the fibrouscapsule located beneath the rectus muscles of the eye. Such expansion orthe fibrous capsule can stretch and tighten the rectus muscles, therebyinducing heterotropia and impairing the motility of the eye in thequadrant wherein the implant is located. Additionally, due to the sizeof some of these shunt devices, the bulky presence of the device itselfwithin the subconjunctival space can cause scleral erosion, changes inthe natural curvature of the eye, or damage to adjacent vasculature andtissue. Other problems associated with the use of implantable shuntdevices for the treatment of glaucoma involve friction and wear impartedby the implanted shunt device, irritation of the iris endothelium causedby insertion of the shunt device into the anterior chamber, andmigration of microbes, cells, proteins or other matter through the lumenof the shunt device and into the anterior chamber of the eye.

Also, the surgical procedures used to implant the prior art fluidshunting devices have typically been laborious in nature and havetypically required that suturing of the fluid shunting device to thesurrounding tissue of the host, to hold the fluid shunting device at itsdesired location within the eye. The installation of sutures to anchorthe implanted fluid shunting device is time consuming and, in caseswhere such sutures are not properly placed, can result in undesirabletugging, traction or stress on the surrounding tissue and/ordisconfiguration of the implanted device. Also, the installation of suchsutures can result in unintentional, iatrogenic perforation of theanterior or posterior chabber of the eye, with resultant leakage ofaqueous or vitreous humor and/or resultant cellular ingrowth andopacification of the aqueous and/or vitreous humor.

ii. Hydrocephalus

Another disorder in which the build-up of abnormal fluid pressure is ahallmark is hydrocephalus. In hydrocephalus, excessive amounts ofcerebrospinal fluids accumulate within skull, generally resulting inelevated intracranial pressure. The chronic elevation in intracranialpressure caused by such excessive cerebrospinal fluid within the skulltypically results in enlargement of the head, prominence of theforehead, brain atrophy, mental deterioration, and convulsions.Hydrocephalus is maybe of congenital origin or may be an acquireddisease. In some patients, hydrocephalus is of sudden onset while inothers it is slowly progressive.

In addition to various pharmacologic therapies, the surgical approach totreatment of hydrocephalus often involves the implantation of a shuntwhich facilitates drainage of excess cerebrospinal fluid from theintracranial space, to other areas of the body wherein it can betolerated-most often into the peritoneal cavity. In addition to glaucomaand hydrocephalus, numerous other diseases and disorders involve thebuildup of excessive fluid within one or more anatomical spaces (i.e.,cavities) of the body, and may be effectively treated by shunting of theexcessive fluid from the affected body space (i.e., body cavity) toother region(s) of the body. However, in many cases, it is desirablethat an implantable shunt device be used, and that such shunt device bevalved or pressure-regulated such that only excessive fluid will beremoved from the affected body cavity, while allowing the normal amountof such fluid to remain within the affected body cavity, so long as thepressure within the cavity is in the normal range. Thus, it is desirablefor the implanted shunt device to include a pressure-sensitive openingor other pressure-actuated valving apparatus which will allow fluid toflow out of the affected body cavity only when the fluid within the bodycavity has exceeded a predetermined maximum pressure.

One complication associated with the use of implantable shunt devices todrain fluid from body cavities is that proteins, cellular matter, orother debris may block the lumen of the shunt tube thereby interferingwith the drainage of fluid through the tube. Also, proliferation oftissue or blebs may compress, collapse, or block the shunt tube.Moreover, pathogenic microorganism or irritating proteins or othermatter may migrate through the lumen of the shunt tube into the affectedbody cavity in a manner which can lead to iatrogenic infection,irritation or inflammation of the affected body cavity.

Given the above-summarized limitations and drawbacks associated with theimplantable fluid-shunting devices of the prior art, it is apparent thatno single fluid-shunting device has proven to be optimal for allapplications. Accordingly, there exists a need in the art for thedevelopment for new implantable fluid-shunting devices which include: a)means for valving or pressure-regulation of the fluid outflow, b) meansfor preventing microbes, proteins, cells or other matter from cloggingthe shunt or migrating through the shunt in to the affected body cavityand/or c) means for anchoring the fluid-shunting device in its desiredimplanted position, without the need for suturing of the device to theadjacent tissue.

SUMMARY OF THE INVENTION

The present invention provides implantable devices for shunting ordraining fluid from one intracorporeal location to another. In general,the implantable devices of the present invention comprise an elongatetube having a lumen extending longitudinally therethrough and adiffusion chamber mounted on the proximal end of the tube. The distalend of the tube is open, while the proximal end of the tube is closed. Apressure-openable aperture is formed in a proximal portion of the tubewhich extends into the interior of the diffusion chamber. Suchpressure-openable aperture will open when the pressure of fluid withinthe lumen of the tube exceeds a predetermined maximum pressure. In thismanner, fluid will be permitted to flow from the distal end of the tube,through the lumen of the tube, through the pressure-openable apertureand into the interior of the diffusion chamber. Thereafter, such fluidmay diffuse outwardly through the diffusion chamber and into thesurrounding tissues or spaces of the body. The diffusion chamber ispreferably formed of material which will prevent unwanted matter (e.g.,proteins, solid particles greater than a predetermined size, or hostcellular matter, such as tissues or individual cells), from entering theinterior of the diffusion chamber and (a) interfering with the desiredopening and closing of the pressure-openable aperture or (b) migratingthrough the lumen of the tube and into the region of the body adjacentthe distal end of the tube.

In accordance with the invention, there are provided implantable deviceswhich may be utilized for numerous fluid-shunting applications,including a) the treatment of glaucoma wherein aqueous humor is shuntedfrom the anterior chamber of the eye and b) the treatment ofhydrocephalus wherein cerebrospinal fluid is shunted from theintracranial space into another body cavity (e.g., the peritonealcavity).

Further in accordance with the invention, there are provided fluidshunting devices which are implantable in the eye of a mammalianpatient, within a subconjunctival pocket formed between two rectusmuscles which are anatomically attached to the eye at spaced-apartlocations, to control the pressure of fluid within the anterior chamberof the eye without the use of sutures to hold the device in its desiredimplanted position. A sutureless implantable device in accordance withthis aspect of the invention may comprise a) a tube which has a proximalend, a distal end, a side wall, and a lumen extending longitudinallytherethrough, b) a diffusion chamber which has an inner cavity formedtherewithin. The diffusion chamber of the device is mounted on theproximal end of the tube, such that fluid which enters the distal end ofthe tube may flow through the lumen of the tube and into the innercavity of the diffusion chamber. The distal end of the tube isinsertable into the anterior chamber of the eye while the diffusionchamber remains positioned within a subconjunctival pocket, posterior tothe limbus. The diffusion chamber has a posterior portion which is widerthan the distance between the locations at which the adjacent rectusmuscled are attached to the eye, and an inter-muscular portion which isslightly narrower than the distance between the rectus muscle attachmentpoints. Preferably, the diffusion chamber also has an anterior portionwhich like its posterior portion, is wider than the distance between theadjacent rectus muscle attachment points. Such preferred sizing andconfiguration of the diffusion chamber allows it to be implanled withinthe subconvunctival pocket with its inter-muscular portion between therectus muscle attachment points, its anterior portion extending anteriorto the rectus muscle attachment points, and its posterior portionextending posterior to the rectus muscle attachment points. When soimplanted, the diffusion chamber will remain in substantially fixedposition and will be prevented by its engagement with the adjacentrectus muscles from undergoing substantial migration or movement in thelongitudinal or lateral directions, without the need for sutures toanchor the diffusion chamber in place. Also, the diffusion chamber maybe formed in a generally concave configuration which is analogous to thecontour of the ocular bulb, thereby allowing the device to fit easilyupon the scleral floor of the subconjunctival pocket, with minimaloutward protrusion or tenting of the conjunctival tissue, and minimaldiscomfort to the patient.

Further objects and advantages of the present invention will becomeapparent to those skilled in the art upon reading and understanding thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of an implantablefluid-shunting device of the present invention.

FIG. 2 is a longitudinal sectional view through line 2--2 of FIG. 1.

FIG. 3 is an enlarged longitudinal sectional view of the proximal-mostportion of the fluid-carrying tube component of the device of FIG. 1.

FIG. 4 is a cross-sectional view through line 4--4 of FIG. 1.

FIG. 5 is partial transverse sectional view through a portion of a humaneye showing an implantable fluid shunting device of the presentinvention positioned therewithin to relieve excessive pressure withinthe anterior chamber of the eye.

FIG. 6 is a schematic showing of a human body wherein an implantablefluid-shunting device of the present invention has been surgicallyinstalled to drain excessive cerebrospinal fluid from the brain to theperitoneal cavity.

FIGS. 7a-7g are partial perspeclive views of alternative embodiments ofthe implantable fluid-shunting device of the present invention.

FIG. 8 is a perspective view of a sutureless implantable fluid shuntingdevice of the present invention useable to control intraoccular pressurein glaucoma patients.

FIG. 9 is a longitudinal sectional view trough line 9--9 of FIG. 8.

FIG. 10 is a schematic showing of a human eye having the device of FIG.10 implanted therein using a sutureless implantation technique of thepresent invention.

FIG. 11 is a top plan view of view of the preferred diffusion chamberconfiguration for the device shown in FIGS. 8-10.

FIG. 12 is a top plan view of an alternative diffusion chamberconfiguration for the device shown in FIGS. 8-10.

FIG. 13 is a flow diagram for a sutureless method for implanting a fluidshunting device of the type shown in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description, and the accompanying drawings towhich it refers are provided for purposes of exemplifying andillustrating representative examples and embodiments of the inventiononly, and are not intended to limit the scope of the invention in anyway. Indeed, no effort has been made to exhaustively illustrate anddescribe all possible embodiments and configurations in which thepresent invention may take physical form.

i. Construction and Configuration of the Fluid Shunting Device

With reference to FIGS. 1-4, there is shown a first embodiment of animplantable fluid shunting device 10 comprising an elongate tube 12having a lumen 14 extending longitudinally theretlirough and a diffusionchamber 20 mounted on the proximal end thereof. The tube 12 has an opendistal end 16, a closed proximal end 18 and a pressure openable aperture30 which is located in a proximal portion PP of the tube 12 whichextends into the interior of the diffusion chamber 20.

In this regard, the diffusion chamber 20 is mounted on the tube 12 suchthat the proximal portion PP of the tube 12 adjacent the proximal end 18thereof, extends into the inner cavity 26 of the diffusion chamber 20.The diffusion chamber 20 is mounted in sealing contact upon the outersurface of the tube 12 such that fluid which flows out of the tube 12into the inner cavity 26 of the diffusion chamber 20 will not freelyleak therefrom. The diffusion chamber 20 is preferably formed ofmembranous material (e.g., permeable or semipermeable membrane material)which will permit the fluid which is desired to be drained by the tube12 to flow from the inner cavity 26 of the diffusion chamber, outwardlyand into the region of the body wherein the diffusion chamber 20 ispositioned, while preventing predetermined types of unwanted matter(e.g., proteins, solid particles which are greater than a predeterminedsize, etc.) from passing inwardly through such membrane and into theinner cavity 26 of the diffusion chamber 20. Additionally, the materialof the diffusion chamber 20 will prevent host cellular matter (e.g.,tissues or cells such as fibroblasts, endothelium, epithelium, bloodcells) from invading (e.g., ingrowing or migrating) the outer surface orinner lumen of the tube 12 and/or the inner cavity 26 of the diffusionchamber 20.

In the particular embodiment shown in FIGS. 1-3, diffusion chamber 20 isconstructed of an upper membrane wall 22a and lower membrane wall 22b.The upper and lower membrane walls 22a, 22b are sealed to one another attheir edges to form a sealed perimeter flange 24. Such sealing of theupper and lower membrane walls 22a, 22b also forms a fluid-tight sealwith the tube 12, while allowing the proximal portion PP of the tube 12to extend into the inner cavity 26 of the diffusion chamber 22.

In the embodiment shown in FIGS. 1-3, suture passage apertures 36 areformed in the diffusion chamber 20 to facilitate suturing of the device10 at it's desired position within the body. Also, tissue ingrowthapertures 34 are formed in the diffusion chamber such that tissue maygrow through such apertures 34, thereby firmly anchoring the diffusionchamber 20 in a substantially fixed position within thesurgically-created pocket in which it is implanted.

Also in the embodiment of FIGS. 1-3, an optional suture tab 38 havingsuture passing apertures 40 is affixed to the outer surface of the tube12, at a spaced distance proximal to the distal end 16 of the tube 12 tofurther facilitate suturing of the tube 12 in a desired position withinthe body.

Also in the embodiment of FIGS. 1-3, an optional concave abutment flange42 is formed on the outer surface of the tube 12 to facilitate andmaintain proper positioning of the tube 12 when implanted within thebody in the glaucoma-treatment application described in detailherebelow. It will be appreciated that, although the embodiment shownuses a concave abutment flange 42, such abutment flange 42 may be ofnumerous different configurations to facilitate and maintain the desiredpositioning of the tube 12 in various other anatomical structures andlocations of the body.

The particular details and sizing of this concave abutment flange 42 inconnection with a particular application of the invention for thetreatment of glaucoma is described in more detail herebelow, and shownin FIGS. 5. In many glaucoma treatment applications, it will bedesirable for such concave abutment flange 42 to have a width W ofapproximately 3 mm, a depth D of approximately 1 mm, and a height H ofapproximately 1 mm.

The pressure-openable aperture 30 may specifically comprise a slitaperture 30 as shown in the drawings. Such slit aperture 30 is formed inthe wall of the proximal portion PP of the tube 12, to facilitateoutflow of fluid from the lumen 14 of the tube 12 into the inner chamber26 of diffusion chamber 20. This pressure-openable slit aperture 30 isbiased to a closed configuration whereby the opposite sides of the slitaperture 30 are in sealing contact with one another to prevent fluidfrom flowing from the lumen 14 of the tube 12 into the inner cavity 26of the diffusion chamber 20 so long as the fluid pressure within thelumen 14 of the tube 12 is below a predetermined maximum pressureP_(MAX). However, the pressure-openable slit aperture 30 is configuredand constructed so as to spread apart (i.e., open) when the fluidpressure within the lumen 14 of the tube 12 exceeds such predeterminedmaximum pressure P_(MAX), thereby allowing fluid to flow from the lumen14 of tube 12 into the inner cavity 26 of the diffusion chamber 20 untilthe fluid pressure within the lumen 14 of the tube 12 falls below apredetermined aperture closing pressure P_(CLS), at which time thebiasing of the pressure-openable slit aperture 30 will cause such slitaperture 30 to once again assume its closed configuration. Thepredetermined maximum pressure P_(MAX) and the predetermined apertureclosing pressure P_(CLS) will be determined on the basis of the intendedapplication of the device 10, to facilitate drainage of fluid from abody cavity wherein the open distal end 16 of the tube 12 is located,into the diffusion chamber 10 when such pressure exceeds thepredetermined maximum pressure P_(MAX), but to prevent such fluidpressure within the body cavity from failing below the predeterminedclosing pressure P_(CLS) so as not to inadvertently drain too much ofsuch fluid from the body cavity. In this manner, the amount of fluidleft within the affected body cavity should be sufficient to perform theintended physiological functioning of the fluid (if any), but such fluidwill be prevented by the device 10 from over-accumulating within thebody cavity in a manner which creates excessive or non-physiologicalpressure within the body cavity.

The specific size, shape, orientation and formation of thepressure-openable slit aperture 30 may vary, depending upon the desiredpredetermined maximum pressure P_(MAX) and predetermined closingpressure P_(CLS). In the particular embodiment shown, the predeterminedmaximum pressure P_(MAX) which will cause the pressure-openable slitaperture 30 to open is a function of the thickness T of the wall of thetube, the width or thickness of the tool utilized to make thepressure-openable slit aperture 30 in the wall of the tube 12, and theangle A of such slit aperture 30 relative to a radial line or ray Rwhich is projectible at 90° to the longitudinal axis LA of the tube 12.When the tool or instrument utilized to make the pressure-openable slitaperture 30 is of minimal width so as not to create a slit which isincapable of assuming a fully closed configuration, the factors whichwill determine the predetermined maximum pressure P_(MAX) at which thepressure-openable slit aperture 30 will open are a) the wall thickness Tof the tube 12, b) the angle A of the slit aperture 30 relative to thetransverse axis (e.g., radius line FR) of the tube 12, c) the length Lof the slit aperture 30, and d) the internal diameter ID of the tube.With respect to the angle A of the slit aperture 30 relative to theradial line or ray R of the tube, it is to be appreciated that inembodiments such as that shown in FIG. 4 wherein the lumen 14 of thetube 12 is round, the slit aperture 30 will form angle A relative to aradius line R which is projected from the inner end of the slit aperture30 to the centerpoint of the round lumen 14. However, variousalternative configurations may be employed wherein the lumen 14 of thetube is other than round, and in such alternative configurations theangle A of the slit aperture 30 will be defined relative to a transverseaxis projected from the inner end of the slit aperture 30 to acenterpoint or center-of-flow point within the lumen 14 of the tube 12.In either instance, the angle A of the slit aperture 30 relative to suchradial line or ray R will determine the amount of tube material whichthe slit aperture 30 must penetrate through, thereby determining atleast in part the amount of fluid pressure which will be required tospread apart the adjacent sides of the slit aperture 30 to cause openingof the slit aperture 30. For example, with reference to the showing ofFIG. 4, if the slit aperture 30 were to extend straight through the wallof the tube 12, the angle A would be 180°, and the slit aperture 30would pass through the minimum amount of tubular material determined bythe wall thickness of the tube 12. However, as the angle A decreasesfrom 180° to 90°, the amount of tubular material through which the slitaperture 30 must pass will increase, thereby requiring greater pressureto part the opposite sides of the slit aperture 30 to accomplish openingthereof. Thus, it is in this manner that the angle A of the slitaperture 30 relative to the radial line or ray R of the tube 12 willfunction as one of the variables which are determinative of thepredetermined maximum pressure P_(MAX) and/or the predetermined closingpressure P_(CLS) of the slit aperture 30.

It will be appreciated that the tube 12 and diffusion chamber 20 may beformed of any material which is suitable for the particular applicationfor which the device 10 is to be used. Examples of materials of whichthe tube 12 may be formed include, but are not necessarily limited tosilicone, hydrogels, polyurethanes, polyesters, latex, natural rubbers,and, cellulosics. Examples of the materials of which the diffusionchamber may be formed include, but are not necessarily limited to,cellulose acetate, cellulosics, polyesters, polyfluorocarbons,hydrogels, polyolefins, a hydrogel made from at least one hydrophilicmonomer and at least one olefinic/polyolefinic cross-linker, and, othernatural polymers.

ii. Application of the Invention for Glaucoma Treatment

A. Implantantion of the Device to Control Intraoccular Pressure

FIG. 5 shows the device of FIG. 1, implanted within the human eye fortreatment of glaucoma. The anatomical structures shown in FIG. 5 arelabeled in accordance with the following:

    ______________________________________                                        Anterior Angle          AA                                                    Anterior Chamber        AC                                                    Ciliary Body            CB                                                    Conjunctiva             CON                                                   Cornea                  COR                                                   Iris                    IR                                                    Lens                    L                                                     Sclera                  SC                                                    Sinus Venosus Sclerae   SVS                                                   Suspensory Ligaments    SL                                                    ______________________________________                                    

In this application of the device the tube 12 will typically have anouter diameter of approximately 0.6 mm, an inner diameter ofapproximately 0.3 mm and a length of approximately 40-45 mm. The concaveabutment flange 42 will be positioned approximately 5 mm from the distalend 16 of the tube 12, and will have a height H of approximately 1 mm, awidth W of approximately 3 mm and a depth D of approximately 1 mm.

The shape of the concave abutment flange 42 may be other than circular,and preferably may be oval shape in the manner depicted in the figures.Such oval configuration of the concave abutment flange 42 willfacilitate the desired passage of the flange 42 in a collapsedconfiguration through the opening formed into the anterior chamber AC ofthe eye, and will thereafter permit the fully deployed and uncollapsedflange 42 to properly seat or nest within the peripheral corner of theanterior chamber AC, in the manner shown in FIG. 5.

As shown, the diffusion chamber 20 and proximal portion of the tube 12are implanted in a cavity formed between the conjunctiva CON and scleraSC, on the lateral aspect of the ocular bulb. The diffusion chamber 20may be doubled over or folded to facilitate insertion through arelatively small incisions and may subsequently be opened or unfoldedwhile in the surgically-created pocket of tissue formed between theconjunctiva CON and sclera SC. The distal end 16 of the tube is advancedthrough an opening formed in the sclera, inboard of the sinus venosussclerae SVS. The concave abutment flange 42 is passed through thesurgically formed opening in the sclera and is retracted so as to be infirm abutment with the sclera and/or adjacent tissue, therebymaintaining the tube 12 in its desired longitudinal position with theappropriate length of tube 12 extending into the anterior chamber AC.Suture tab 38 is secured to the is adjacent tissue of the conjunctivaCON by way of sutures, thereby affixing the distal portion of the tube12 in its desired position, and maintaining the concave abutment flange42 in contact with the sclera and/or adjacent tissue as describedhereabove.

If necessary or desirable, the diffusion chamber 20 of the device 10 maybe initially secured within its desired implantation position by passingsutures through the suture-receiving apertures 36, as shown. Followingimplantation, tissue will ingrow through tissue ingrowth apertures 34 tofurther facilitate anchoring and attachment of the diffusion chamber 20to the surrounding tissue of the conjunctiva CON and sclera SC. Thus,with the device 10 implanted within the eye in the manner shown in FIG.5, excess aqueous humor in the anterior chamber AC will enter the opendistal end 16 of the tube 12, and will flow through the lumen 14 of thetube 12. When the pressure of aqueous humor within the lumen 14 of thetube 12 exceeds the predetermined maximum pressure P_(MAX) thepressure-openable split aperture 30 will be caused to open, therebyallowing the access humor to flow out into the inner cavity 26 of thediffusion chamber 20. Such outflow of aqueous humor will continue untilthe pressure of aqueous humor within the lurnen 14 of the tube 12 fallsbelow the predetermined closing pressure P_(CLS) of thepressure-openable slit aperture 30, at which time the pressure-openableslit aperture 30 will once again assume its closed configuration.Thereafter, the pressure-openable slit 30 will remain closed until suchtime as the pressure of aqueous humor within the lumen 14 of the tube 12once again exceeds the predetermined maximum pressure P_(MAX).

For many glaucoma patients, the desired predetermined maximum pressureP_(MAX) will be approximately 15 mm/Hg, and the desired closing pressureP_(CLS) of the pressure-openable slit aperture 30 will be approximately5 mm/Hg. As explained hereabove, the length and angular orientation ofthe pressure-openable slit apertures 30 will be adjusted to providethese desired predetermined maximum pressure P_(MAX) and predeterminedclosing pressure P_(CLS). In this regard, the pressure of aqueous humorwithin the anterior chamber AC of the eye will be prevented fromexceeding the predetermined maximum pressure P_(MAX) of approximately 15mm/Hg, and will also be prevented from falling below the predeterminedclosing pressure P_(CLS) of approximately 5 mm/Hg. Thus, in thisapplication of the present invention, the device 10 will operate tomaintain pressure of aqueous humor within the anterior chamber withinthe 5-20 mm/Hg range, and preferably in a range of approximately 5-15mm/Hg.

Excess aqueous humor which has passed through the tube 12 and into theinner cavity 26 of the diffusion chamber 20 will subsequently diffuseoutwardly through the membrane walls 22a, 22b of the chamber and intothe surrounding tissue. Such fluid will, thereafter, be assimilated bynormal physiological action of the tissues.

In this glaucoma-treatment application, it is preferable that themembrane walls 22a, 22b of the diffusion chamber 20 be formed ofcellulose acetate and/or polyvinylidene fluoride (PVDF), as suchmaterials exhibit desirable host tissue compatibility. This preferredmembrane material will allow the aqueous humor which collects in theinner cavity 26 to diffuse outwardly therethrough, but will preventcellular ingrowth, proteins or particulate matter from passing inwardlyinto the inner cavity 26 of the diffusion chamber 20 where such mattercould a) block or interfere with the pressure-openable slit apertures 30or b) migrate through the lumen 14 of the tube 12 into the anteriorchamber AC of the eye.

Also, in this glaucoma-treatment application, it is preferable that thetube 12 be formed of silicone.

B. Sutureless Implantable Device for Controlling Intraoccular Pressure

FIGS. 8-13 are directed to a sutureless embodiment 10s of theimplantable fluid shunting device 10 described above. With specificreference to FIGS. 8-11, there is shown a sutureless implantable fluidshunting device 10s which comprises an elongate tube 12s having a lumen14s extending longitudinally therethrough and a diffusion chamber 20smounted on the proximal end thereof. The tube 12s has an open distal end16s, a closed proximal end 18s and a pressure openable aperture 30slocated in a proximal portion PP of the tube 12s which extends into theinterior of the diffusion chamber 20s.

The diffusion chamber 20s is constructed of an upper membrane wall 22saand lower membrane wall 22sb. The upper and lower membrane walls 22sa,22sb are sealed or connected to one another at their edges to form asealed perimeter 24s. As shown, the tube 12s extends through a tubepassage aperture 23s formed in the lower membrane wall 22sb of thediffusion chamber 20s, at an angle, such that an anterior portion of thediffusion chamber 20s overhangs the portion of the tube 12s whichextends outside of the diffusion chamber's lower wall 22sb. As in theabove-described suture-anchorable embodiment, the tube 12s of thisdevice 10s is disposed such that the proximal portion PP of the tube 12s(i.e., the portion adjacent its proximal end 18s) extends into the innercavity 26s of the diffusion chamber 20s. The portion of the lowermembrane wall 22sb which surrounds the tube passage aperture 23s issealed to the outer wall of the tube 12s. As a result, any fluid whichflows through the tube 12s and into the inner cavity 26s of thediffusion chamber 20s will not freely leak therefrom.

The diffusion chamber 20s is preferably formed of membranous material(e.g., permeable or semipermeable membrane material) which will permitthe fluid which is desired to be drained by the tube 12s to flow fromthe inner cavity 26s of the diffusion chamber 20s, outwardly and intothe region of the body wherein the diffusion chamber 20s is positioned,while preventing predetermined types of unwanted matter (e.g., proteins,solid particles which are greater than a predetermined size, etc.) frompassing inwardly through such membrane and into the inner cavity 26s ofthe diffusion chamber 20s. Additionally, the material of the diffusionchamber 20s will prevent host cellular matter (e.g., tissues or cellssuch as fibroblasts, endothelium, epithelium, blood cells) from invading(e.g., ingrowing or migrating) the outer surface or inner lumen of thetube 12s and/or the inner cavity 26s of the diffusion chamber 20s.

The pressure-openable aperture 30s may comprise a pressure-openable slitaperture, as shown in FIG. 9. Such slit aperture 30s may be sized,configured, formed, located and operated in the same manner as the slitaperture 30 of the suture-anchorable device 10 shown in FIGS. 1-3 anddescribed hereabove.

As illustrated in FIG. 10, the diffusion chamber 20s of this device 10sis specifically sized and shaped such that it may be positioned within asubconjuntival pocket which has been surgically formed in one superiorquadrant of the eye, between the locations at which two (2) adjacentrectus muscles RM attach to the ocular bulb OE (e.g., between theattachment point AP of the lateral rectus muscle and the attachmentpoint AP of the superior or inferior rectus muscle). The width W₁ ofthat portion of the diffusion chamber 20s which resides posterior to theattachment points AP of the adjacent rectus muscles RM between which thedevice 10s is implanted, is wider than the distance D between thosemuscle attachment points AP. Preferably, the width W₃ of that portion ofthe diffusion chamber 20s which resides anterior to those attachmentpoints AP of the adjacent rectus muscles RM is also wider than thedistance D between those muscle attachment points AP. The portion (i.e.,the "inter-muscular" portion) of the diffusion chamber 20s which residesbetween the attachment points AP of the adjacent rectus muscles RM has awidth W₂ which is at least slightly narrower than the distance D betweenthose muscle attachment points AP. As a result, when the device 10s isimplanted in the position shown in FIG. 10, it will be prevented frommigrating in either lateral direction LD1, LD2 by the abutment of thelateral sides of the diffusion chamber 20s against the attachment pointsAP of the rectus muscles RM. Additionally, the device 10s will beprevented from migrating in either the anterior direction AD orposterior direction PD by the abutment of the edges of the posteriorportion (i.e., the portion of width W₁) and anterior portion (i.e., theportion of width W₃) of the diffusion chamber against the attachmentpoints AP of the adjacent rectus muscles. Also, the device 10s isdeterred from migrating in any direction by the engagement of the tube12s, which extends downwardly through the lower wall 22sb of thediffusion chamber 20s, with the walls of the the puncture tract throughwhich the tube extends from the subconjunctival pocket in which it ispositioned, into the anterior chamber AC of the eye. Still further, thedevice 10s is prevented from migrating in the posterior direction PD bythe bottoming out of the posterior portion of the diffusion chamber 20sagainst the posterior end of the surgically-formed subconjunctivalpocket and/or the abutment of the anterior portion (i.e. the portion ofwidth W₃) against the attachment points AP of the rectus muscles RM ininstances where the width W₃ of that anterior portion AP of thediffusion chamber 20s is wider than the distance D between the muscleattachment points AP. In many applications, it may not be necessary forthe anterior portion AP of the diffusion chamber 20s to be of a width W₃which is wider than the distance D between the rectus muscle attachmentpoints AP, as the potential for posterior migration of the device 10smay be adequately limited by a) the bottoming out of the posterior endof the diffusion chamber 20s against the posterior extent of thesubconjunctival pocket and/or b) the lateral abutment of the tube 12sagainst the walls of the puncture tract through which that tube 12sextends into the anterior chamber AC. However, in cases where thesubconjunctival pocket is deeper than necessary, or where it isotherwise deemed desirable to further restrict the posterior migrationof the device 10s, the surgeon may select a device 10s which has ananterior portion of a width W₃ that is wider than the distance D betweenthe rectus muscle attachment points AP, thereby providing for furtherprevention of undesirable migration in the posterior direction PD.

It will be appreciated that the exact shape and dimensions of thediffusion chamber 20s may vary, while still incorporating theabove-described configurational attributes which allow it to engage andbe held in place by, the adjacent rectus muscle attachment points AP.For example, FIG. 12 shows a diffusion chamber 20s' which, while stillwithin the scope of the present invention, has a shape which isdifferent from that shown in FIGS. 8-11.

It will be further appreciated that this sutureless embodiment of thedevice 10s may be devoid on any suture passage apertures or suture tabs,as no sutures are required to be placed in the device 10s to hold it inplace following implantation.

C. A Preferred Technique for Iniplantation of the Sutureless Device inthe Eye to Control Intraoccular Pressure

FIG. 13 is a flow diagram showing the steps of a preferred technique forimplanting the sutureless fluid shunting device 10s within the eye inthe manner illustrated in FIG. 10.

Step 1: Formation of Conjunctival Incision and Subconjunctival Pocket

A curved or straight incision IN of approximately 5 millimeters lengthis formed through the conjunctival layer, at the limbus. Thereafter,standard ophthalmological surgical technique is used to separate theconjunctival tissue from the underlying scleral tissue, thereby creatinga subconjunctival pocket in a superior quadrant of the eye, posterior tothe incision IN and between adjacent rectus muscles (e.g., between thesuperior rectus muscle RM and the lateral rectus muscle RM).

Step 2: Insertion of the Implantable Fluid Shunting Device

With the diffusion chamber 20s of the device 10s in a collapsed (e.g.,folded, rolled or compressed) state, the diffusion chamber 20s isinserted, posterior end first, through the incision IN and into thesubconjunctival pocket. Thereafter, open (e.g., unfold, unroll ordecompress) the diffusion chamber so that a) the inter-muscular portionof the diffusion chamber 20s of width W₂ resides between the attachmentpoints AP of the adjacent rectus muscles RM, and b) the posteriorportion of the diffusion chamber 20s of width W₁ resides posterior tothe attachment points AP of rectus muscles RM.

Step 3: Creation of Trans-Trabecular Puncture Tract

A needle or other puncturing member (e.g., a 23 gage needle) is theninserted through the incision IN and advanced, on a path which issubstantially parallel to the iris, to create a puncture tract whichextends from a location on the anterior scleral surface (i.e., the floorof the surgically formed subconjunctival pocket) approximately 1.5millimeters proximal to the limbus into the anterior chamber AC. Ifnecessary, a quantity of viscoelastic substance (e.g., hyaluronic acidor methyl cellulose) or other temporary embolization material may bedeposited in the freshly-formed puncture tract to prevent backflow ofaqueous humor from the anterior chamber and the possibility of resultanthypotony, while the tube 12s is being prepared for insertion through thepuncture tract.

Step 4: Insertion of Tube Into Anterior Chamber

The tube 12s is then inserted, distal end first, through the puncturetract until the distal end 16s of the tube enters the anterior chamberAC but does not touch the iris IR or corneal epithelium. The surgeon maytrim the tube to length prior to insertion, to ensure that the distalend 16s of the tube 12s will reside at its desired position within theanterior chamber AC.

Step 5: Closure of Conjunctival Incision

The small conjunctival incision IN is then closed by way of anabsorbable suture or other suitable closure means (e.g, a polymer filmwhich may be applied to the surface of the conjunctiva to hold theincision IN closed until healed).

By the above-described five-step procedure, the implantable fluidshunting device 10s of the present invention may be surgically implantedin the eye, without the use of sutures (i.e., stitches, staples, clips,etc) to hold or anchor the device 10s at its desired position within theeye, relying instead on the engagement and interaction of the wallsand/or edges of the diffusion chamber 20s and/ot tube 12s with thesurrounding tissues, to hold the device 10s in its desired implantationposition.

iii. Application of the Invention for Treatment of Hydrocephalus

FIG. 6 shows a variant of the device shown in FIGS. 1-3, implanted inthe human body for treatment of hydrocephalus.

In this application of the device 10, the device 10 is devoid of theoptional concave abutment flange 42. The device 10 is implanted suchthat the diffusion chamber 20 is positioned within the peritoneum, andthe tube 12 is passed subcutaneously over the thorax, neck and into thebase of the skull. The distal portion of the tube 12 may reside in thespace between the brain and cranium, or may be inserted into a ventricleof the vein in accordance with the applicable treatment technique forthe particular case of hydrocephalus being treated. The optional suturetab 38 may be employed to anchor the tube 12 in its desired positionwithin the cranial vault. Also, the suture passage apertures 34, 36formed on the diffusion chamber 20 may be utilized to suture thediffusion chamber 20 in its desired position within the patientsabdomen.

When the device 10 has been implanted in the manner shown in FIG. 6,excess cerebrospinal fluid will enter the open distal end 16 of the tube12 and will flow through the lumen 14 of the tube. When thecerebrospinal fluid pressure within the lumen 14 of the tube 12 exceedsthe predetermined maximum pressure P_(MAX), the pressure-openable slits30 will open, thereby allowing the excess cerebrospinal fluid flow intothe inner cavity 26 of the diffusion chamber 20. Such outflow ofcerebrospinal fluid will continue until the pressure of cerebrospinalfluid within the lumen 14 of the tube 12 falls below the predeterminedclosing pressure P_(CLS).

In many hydrocephalus patients, the desired predetermined maximumpressure P_(MAX), for treatment of hydrocephalus will be in the range of10-20 mm/Hg, and the desired predetermined closing pressure P_(CLS) willbe in the range of 0-10 mm/Hg. In this manner, the pressure ofcerebrospinal fluid within the ventricle of the brain, or otherwisewithin the cranium, may be maintained in a prescribed range, such as apreferred range of 5-14 mm/Hg, in accordance with the particularpredetermined P_(MAX) and P_(CLS) of the device 10.

iv. Alternative Configurations/Applications of the Invention

FIGS. 7a-7g show alternative embodiments of the device 10a-10g whereinthe diffusion chamber 20a-20g is of varying configuration, to facilitateuse of the device 10-10g in various other applications.

It will be appreciated that, the diffusive surface area of the diffusionchamber 20a-20g may be altered by changing the shape of the diffusionchamber 20-20g. Moreover, alterations or variations in the shape of thediffusion chamber 20-20g, especially those wherein openings orinvaginations are formed in the diffusion chamber 20-20g, may form areasinto which tissue may ingrow so as to soundly anchor and fix thediffusion chamber 20-20g within its desired implantation position. Theutilization of indigenous tissue ingrowth as a means for physicalfixation and anchoring of the diffusion chamber 20-20g is desirable inthat it may eliminate the need for the use of permanent sutures foranchoring of the diffusion chamber 20-20g, as sutures may tend to exertphysical stress or force upon the diffusion chamber 20-20g and/oradjacent tissue. Furthermore, promoting tissue ingrowth within specificregions of the diffusion chamber 20-20g may firmly anchor and hold thediffusion chamber 20-20g in its desired implantation position so as todeter or prevent post-surgical micromovement of the device 10. In thisregard, the embodiments illustrated in FIGS. 7a-7g incorporate variousmodifications wherein multiple projections, invaginations, and otherconfigurational variations are formed in the diffusion chamber 20a-20g.

Additionally, it will be appreciated that the shape of the diffusionchamber may be modified to facilitate a) folding of the diffusionchamber to facilitate its insertion into a specific area of the body andb) ease of placement and retention of the diffusion chamber 20a-20g atits intended site of implantation.

The alternative embodiments shown in FIGS. 7a-7g are merely examples ofthe multitude of shapes and configurations in which the diffusionchamber 20a-20g may be formed and, accordingly, the intended shape orconfiguration of the diffusion chamber 20 shall not be limited to onlythose shapes and configurations shown in the drawings, but shall includeany and all other shapes or configurations in which the diffusionchamber 20 may be formed.

In particular, the diffusion chambers 20a, 20e, 20g shown in FIGS. 7a,7e, and 7g, respectively, have curved or tapered outer edges whereby theproximal end of the diffusion chambers 20a, 20e, 20g is narrower thanits distal end, thereby facilitating easy extraction and removal of thediffusion chamber 20a, 20e, 20g, if and when such removal is desired.

The invention has been described hereabove with reference to certainpresently preferred embodiments, and no attempt has been made todescribe all possible embodiments in which the invention may takephysical form. Indeed, numerous modifications, additions, deletions andalterations may be made to the above-described embodiments withoutdeparting from the intended spirit and scope of the invention.Accordingly, it is intended that all such additions, deletions,modifications and alterations be included within the scope of thefollowing claims.

What is claimed is:
 1. A fluid shunting device which is implantable inthe eye of a mammalian patient, within a subconjunctival pocket formedbetween two rectus muscles which are anatomically attached to the eyewith a spaced distance therebetween, said device being operative tocontrol the pressure of fluid within the anterior chamber of the eyewithout the use of sutures to hold the device in its desired implantedposition, said device comprising:a tube having a proximal end, a distalend, a side wall, and a lumen extending longitudinally therethrough;and, a diffusion chamber having an inner cavity formed therewithin, aposterior portion of a width greater than the distance between saidrectus muscles, and an inter-muscular portion of a width less than thedistance between said rectus muscles, wherein said diffusion chambercomprises at least one membrane formed of material which will allow saidfluid to diffuse out of the inner cavity of said diffusion chamber,while preventing predetermined types of matter from passing through saidmembrane into the inner cavity of said diffusion chamber; said diffusionchamber being mounted on the proximal end of the tube such that fluidwhich enters the distal end of the tube may flow through the lumen ofthe tube and into the inner cavity of the diffusion chamber; and, saiddevice, when implanted in the eye, being devoid of sutures attaching thedevice to the eye.
 2. The device of claim 1 wherein the distal end ofthe tube is insertable into the anterior chamber of the eye, and thediffusion chamber is positionable within the subconjunctival pocket,posterior to the limbus, such that its inter-muscular portion is betweenthe locations at which said rectus muscles are anatomically attached tothe eye, and its posterior portion is posterior to the locations atwhich said rectus muscles are anatomically attached to the eye.
 3. Thedevice of claim 1 wherein the diffusion chamber further comprises:ananterior portion of a width greater than the distance between saidrectus muscles, said device being further positionable within thesubconjunctival pocket such that its anterior portion is anterior to thelocations at which said rectus muscles are anatomically attached to theeye.
 4. The device of claim 1 wherein a pressure-openable aperture isformed in said tube, said pressure-openable aperture being biased to aclosed configuration, and being openable in response to fluid pressureexceeding a predetermined maximum pressure, within the lumen of saidtube distal to said pressure openable aperture.
 5. The device of claim 1wherein the diffusion chamber has a lower wall through which a tubepassage aperture is formed, a proximal portion of said tube beinginserted through said tube passage aperture and into the inner cavity ofthe diffusion chamber, the lower wall of said diffusion chamber beingsealed to the wall of said tube.
 6. The device of claim 1 wherein saidmembrane is a permeable membrane.
 7. The device of claim 1 wherein saidmembrane is a semipermeable membrane.
 8. The device of claim 1 whereinsaid predetermined types of matter which said membrane will prevent frompassing into said diffusion chamber are selected from the group ofmatter types consisting of:a) microbes; b) proteins; c) particlesexceeding 5 microns in size; and, d) host cellular matter.
 9. The deviceof claim 1 wherein said diffusion chamber comprises material which willallow said fluid to diffuse out of the inner cavity of the diffusionchamber, but will prevent host cellular matter from entering the innercavity of the diffusion chamber.
 10. The device of claim 1 wherein saiddiffusion chamber is formed at least partially of materials selectedfrom the group of materials consisting of:cellulose acetate;cellulosics; polyesters; polyfluorocarbons; polyvinylidene fluoride;hydrogels; polyolefins; a hydrogel made from at least one hydrophilicmonomer and at least one olefinic/polyolefinic cross-linker; and, othernatural polymers.
 11. The device of claim 1 wherein said tubing isformed at least partially from material selected from the group ofmaterials consisting of:silicone; hydrogels; polyurethanes; polyesters;latex; natural rubbers; and, cellulosics.
 12. The device of claim 1wherein said diffusion chamber comprises:an upper membrane wall havingat least one peripheral edge; and, a lower membrane wall having at leastone peripheral edge; said upper and lower membrane walls being fused toone another about their peripheral edges to form said diffusion chamber.13. The device of claim 4 wherein said pressure-openable aperturecomprises an elongate slit.
 14. The device of claim 13 wherein saidelongate slit is formed in said tube such that said elongate slit issubstantially parallel to the longitudinal axis of the tube.
 15. Thedevice of claim 13 wherein said tube has a radius, and wherein saidelongate slit extends through the wall of said tube at an angle relativeto the radius of which has been predetermined to cause said slit to openwhen a desired maximum pressure P_(MAX) of fluid is present within thelumen of the tube.
 16. A fluid shunting device for suturelessimplantation within a subconjunctival pocket formed in the eye of amammalian patient between two adjacent rectus muscles which areanatomically attached to the eye at spaced apart muscle attachmentlocations defining an inter-muscular distance therebetween, said devicecomprising:a tube having a proximal end, a distal end and lumenextending longitudinally therethrough; and, a diffusion chamber havingan inner cavity formed therewithin, said diffusion chamber being mountedon the proximal end of the tube such that fluid may enter the distal endof the tube, flow through the lumen of the tube into the inner cavity ofthe diffusion chamber and diffuse outwardly through said diffusionchamber, wherein said diffusion chamber comprises at least one membraneformed of material which will allow said fluid to diffuse out ot theinner cavity of said diffusion chamber, while prevention predeterminedtypes of matter from passing through said membrane into the inner cavityof said diffusion chamber; a posterior portion of said device being of awidth greater than the inter-muscular distance, an inter-muscularportion of the device being of a width less than the inter-musculardistance and an anterior portion of the device being of a width greaterthan the inter-muscular distance; said device being implantable withinthe subconjunctival pocket such that its posterior portion situatedposterior to the adjacent rectus muscle attachment locations, itsinter-muscular portion is situated between the adjacent rectus muscleattachment locations and its distal portion is situated distal to therectus muscle attachment locations, the device being thereby prevented,without the use of sutures, from undergoing substantialpost-implantation movement in either the proximal or distal directions;and, said device, when implanted in the eye, being devoid of suturesattaching the device to the eye.
 17. The device of claim 16 wherein thediffusion chamber has a lower wall through which a tube passage apertureis formed, a proximal portion of said tube being inserted through saidtube passage aperture and into the inner cavity of the diffusionchamber, the lower wall of said diffusion chamber being sealed to thewall of said tube.
 18. The device of claim 16 wherein said diffusionchamber comprises:an upper membrane wall having at least one peripheraledge; and, a lower membrane wall having at least one peripheral edge;said upper and lower membrane walls being fused to one another abouttheir peripheral edges to form said diffusion chamber.
 19. The device ofclaim 16 wherein a pressure-openable aperture is formed in said tube,said pressure-openable aperture being biased to a closed configuration,and being openable in response to fluid pressure exceeding apredetermined maximum pressure, within the lumen of said tube distal tosaid pressure openable aperture.
 20. The device of claim 19 wherein saidpressure-openable aperture comprises an elongate slit.
 21. The device ofclaim 20 wherein said elongate slit is formed in said tube such thatsaid elongate slit is substantially parallel to the longitudinal axis ofthe tube.
 22. The device of claim 21 wherein said tube has a radius, andwherein said elongate slit extends through the wall of said tube at anangle relative to the radius of which has been predetermined to causesaid slit to open when a desired maximum pressure P_(MAX) of fluid ispresent within the lumen of the tube.
 23. The device of claim 22 whereinsaid diffusion chamber comprises at least one membrane formed ofmaterial which will allow said fluid to diffuse out of the inner cavityof said diffusion chamber, while preventing predetermined types ofmatter from passing through said membrane into the inner cavity of saiddiffusion chamber.
 24. The device of claim 22 wherein the proximalportion of the device comprises a proximal portion of the diffusionchamber, the distal portion of the device comprises a distal portion ofthe diffusion chamber and the inter-muscular portion of the devicecomprises the portion of the diffusion chamber located between saidproximal potion and said distal portion.
 25. The device of claim 22wherein the distal end of the tube is insertable into the anteriorchamber of the eye, and the diffusion chamber is positionable within thesubconjunctival pocket, posterior to the limbus, such that itsinter-muscular portion is between the locations at which said rectusmuscles are anatomically attached to the eye, and its posterior portionis posterior to the locations at which said rectus muscles areanatomically attached to the eye.
 26. The device of claim 16 whereinsaid tubing is formed at least partially from material selected from thegroup of materials consisting of:silicone; hydrogels; polyurethanes;polyesters; latex; natural rubbers; and, cellulosics.
 27. The device ofclaim 16 wherein said diffusion chamber is formed at least partially ofa material selected from the group of materials consisting of:celluloseacetate; cellulosics; polyesters; polyfluorocarbons; polyvinylidenefluoride; hydrogels; polyolefins; a hydrogel made from at least onehydrophilic monomer and at least one olefinic/polyolefinic cross-linker;and, other natural polymers.
 28. The device of claim 16 wherein saidmembrane is a permeable membrane.
 29. The device of claim 16 whereinsaid membrane is a semipermeable membrane.
 30. The device of claim 16wherein said predetermined types of matter which said membrane willprevent from passing into said diffusion chamber are selected from thegroup of matter types consisting of:a) microbes; b) proteins; c)particles exceeding 5 microns in size; and, d) host cellular matter. 31.The device of claim 16 wherein said diffusion chamber comprises materialwhich will allow said fluid to diffuse out of the inner cavity of thediffusion chamber, but will prevent host cellular matter from enteringthe inner cavity of the diffusion chamber.